CONICET | Buscador de Institutos y Recursos Humanos

Carrageenans are sulfated galactans notably conspicuous in red seaweeds. Theirabundance in renewable sources combined with their already proven biological activitiesand rheological properties has drawn their attention at both industrial and lab levels.Their complex though basically repeating structure has made carrageenans an interestingtarget for chemical modifications. In this way, newly functionalized polysaccharides canbe obtained with enhanced and/or altered properties, either biological or rheological, butstill maintaining fundamental properties such as biocompatibility and biodegradability.This chapter will focus on the different chemical modifications performed up to dateon carrageenans and how these modifications have affected the polysaccharideproperties. The simplest and best-known modification is the so-called alkaline treatment,only possible in carrageenans carrying -D-galactose 6-sulfate units, as they convert into3,6-anhydrogalactose in the polysaccharide, thus increasing their gelling properties. Theincrease or decrease of the negative charge (i.e., oversulfation, desulfation, oxidation ofC-6, etc.) comprises another common group of reactions carried out on thesepolysaccharides that can affect both the physicochemical and biochemical properties.Other reactions such as cationizations, depolymerizations and increases of thehydrophobicity have also been performed on these polysaccharides and have providedlarge variations of the original properties. Furthermore, the carrageenans have been usedas backbones for crosslinking reactions as well as grafting to other polymeric molecules.These new biomaterials are of interest in the biomedical area, as they can be used fordrug delivery and tissue engineering, among other uses.